1. Field of the Invention
The present invention relates to an oxide film formation method and image sensing apparatus.
2. Description of the Related Art
To form an insulating film on a silicon substrate, a semiconductor device manufacturing process uses a method (to be referred to as “thermal oxidation” hereinafter) of forming an oxide film on the surface of the silicon substrate by exposing it to a high-temperature oxidizing ambient. Since, however, thermal oxidation like this is performed at about 1,000° C., impurity diffusion or substrate strain occurs. Therefore, a silicon oxide film formation method replacing thermal oxidation is being developed.
Japanese Patent Laid-Open No. 2000-286259 has disclosed a method (to be referred to as “plasma oxidation” hereinafter) of supplying a gas mixture containing an inert gas and an oxidizing gas such as oxygen, and forming a silicon oxide film by using a plasma generated by applying radio-frequency power (RF power).
In the method of Japanese Patent Laid-Open No. 2000-286259, energy released when the excited inert gas shifts to the ground state is emitted to oxygen molecules, thereby efficiently generating oxygen atoms and oxygen radicals. An oxide film can be formed on a silicon substrate at a low temperature by making these oxygen atoms and oxygen radicals react with silicon.